Inflatable foil sachet, especially for packaging purposes

ABSTRACT

The invention relates to a foil sachet (1) with at least one chamber (7) consisting of an upper and lower foil (2, 3) secured together by a closed seam (5, 6). In order to fill the chambers (7) with a substance, especially air, there is a channel (10, 14) having channel sections (14) opening in the region of a seam (5, 6) and preferably in the region of the corner of the chamber concerned where there is an aperture in said chamber. There are preferably a main (10) and a subsidiary channel (14), wherein the main channel may also run outside the foil sachet (1).

This is a continuation of copending application Ser. No. 07/807,848filed on Feb. 28, 1992, now abandoned.

DE-A 37 05 167 discloses a film bag made of thin plastic film having atleast one chamber consisting of an upper and a lower film interconnectedby a closed-line seam. A narrow tube having small dimensions compared tothe chamber and likewise consisting of a thin film extends through allchambers of the film bag, remaining permeable for a filling medium,generally air, at the points of passage into the chamber at the seams.The tube itself has openings, e.g. perforations, through which airenters the chamber when the bag is filled. When the chamber is filledthe film tube is compressed by the internal pressure in the chamber sothat the openings automatically close.

The seams interconnecting the upper and lower films are preferably weldseams, whereby only the outer walls of the tube are welded to the filmsat the points of passage of the tube during the welding process whilethe film tube remains permeable to air at these points of passage. Thiscan be effected by preparing the film tube in such a way that its innerwalls are moistened e.g. with a medium which prevents such a welding, orby an additional thermal film within the tube which has a higher meltingpoint than the material of the outer wall of the tube.

Further prior art is French patent no. 2.067.530 and French patentapplication no. 2.291.114.

A problem of known film bags is their proper closure, in particular whenstrong long-lasting forces or strong shock-like forces act on the bag.With conventional constructions at least part of the air in the foilbags can flow out, thereby reducing the packaging effect with respect toreliable holding and protection of the object. Also, their production isfrequently complicated.

The invention is based on the problem of stating a film bag of the typein question whose production is simplified and which reliably preventsthe filling medium, i.e. air, from flowing out under virtually alloperating conditions.

This is achieved when the channel has portions connected with thechamber film which are situated near a seam in each chamber, and theopenings into the chambers are provided there. The channel portions withthe openings are preferably situated in the area of the corners of thechambers. They are therefore located in areas where the strongest curvesand the most bends and folds, which repeatedly bend the channel, occurin the inflated film bag, so that the sealing effect is excellent.

It is particularly advantageous if the film bag is formed in such a waythat the channel is divided into a main channel and a side channelbranching off the main channel, whereby the side channel is directedinto the corner of a chamber and the opening into the chamber isprovided there. At least the side channel is in turn connected with thechamber film. The side channel and main channel can be formed e.g. withthe aid of a film strip which is connected with a chamber film e.g. bywelding.

Since the openings from the channel into the chambers are preferablysituated in the chamber corners, the channel arrangement is locatedalong the edge of the film bag, the main channel being disposed outsidethe longitudinally extending edge seam of the chambers when the channelarrangement is separated into a main channel and a side channel. Thisparticularly ensures a uniform filling of the chambers even if aplurality of them are arranged in a row. Furthermore, it makes itpossible to dispose a film bag on each side of the main channel, so thatfilm bags with a plurality of chambers can be produced whereby the bagsare simultaneously very flexible and can be well adapted in shape to theobject to be packaged and protected.

Further embodiments of the invention can be found in the subclaims. Theinvention will be explained in more detail in embodiment examples withreference to the drawing, in which:

FIG. 1 shows a schematic top view of a film bag according to theinvention having three chambers and a film strip stuck on the outside ofthe film bag for forming a channel;

FIG. 2 shows a section along II--II in FIG. 1;

FIG. 3 shows a top view of part of a film strip for forming a mainchannel and a side channel;

FIGS. 4a to 4e each show schematic representations of individual methodsteps during production of a film bag;

FIGS. 5a, 5b and 6a, 6b and 7a, 7b each show top views of part of a filmbag and partial sections through the bag, respectively;

FIGS. 8 to 10 each show schematic representations of film bags; and

FIGS. 11a and 11b show schematic representations of a rod for inflatingfilm bags.

A film bag 1 according to FIG. 1 has an upper film 2 and a lower film 3both made e.g. of polyethylene. Along a row, at the edge of the filmsheets, openings 4 are pierced in upper film 2. The two films are placedone on the other according to FIG. 2 and divided into three chambers 7sealed from one another by longitudinal weld seams 5 at the edges andtransverse weld seams 6. Between adjacent chambers there are twoparallel transverse weld seams 6 in each case, so that the bag can bebent at these points without obstruction. Openings 4 are located in eachcase in or between the corners of chambers 7. Over the total length ofthe film bag in the area of the openings there extends a strip-shapedfilm 8 which is glued on e.g. with the aid of an adhesive 9, wherebyadhesive 9 is applied only at the longitudinal edges as indicated inFIG. 2. The film strip may also be welded along its edges to the upperfilm as indicated on the right in FIG. 2. In an area above openings 4,films 2 and film strip 8 are thus not interconnected, leaving a channel10 which extends over the total length of the film bag. In one end ofthis channel one can insert e.g. an inflating rod which is connected toa compressor. When the other end of the channel is closed and thecompressor switched on, air flows through openings 4 into chambers 7 ofthe film bag which thereby swell up in a cushion shape. When chambers 7are sufficiently filled the compressor is switched off. The internalpressure in the bag presses upper film 2 against strip-shaped film 8 andseals channel 10 from the outside. The sealing effect is furtherincreased by openings 4 being located in an area where the film bag ishighly deformed and curved by the inflation and therefore has folds andbends which additionally block channel 10. The seal is maintained evenif there are high pressures on the bag. The sealing effect is lower thefurther away main channel 10 is from weld seam 5.

At the points where the film strip passes through the transverse weldseams one must then make sure the channel remains permeable for theinflating air.

FIG. 3 shows a section of a film strip 8' in the area of a chamber 7which is connected with one of the chamber films, here by an adhesive 9,in accordance with the above embodiment example. Adhesive 9 is appliedin such a way that a channel pattern consisting of a main channel 10extending in the longitudinal direction of film strip 8' and a sidechannel 14 branching off the main channel and runs parallel thereto toconnect for each chamber. Side channel 14 is disposed in such a way thatwhen the film bag is inflated, indicated by the arrow in main channel10, the air flows in the opposite direction in side channel 14. At theplaces indicated by crosses at the end of side channel 14, openings 4 tothe chamber are provided which are disposed in the corner of theparticular chamber as above. If the film strip is applied to the lowerfilm within the chamber, branch channels 4a extending from side channel14 to the edge of film strip 8' can also be provided, as indicated bybroken lines in FIG. 3, in the area of which the film strip is notconnected with the lower film. The air then passes into chambers 7through these branch channels or openings 4a. Such a channel patternbetween the film strips and one of the chamber films can of course alsobe produced by accordingly disposed weld seams.

FIGS. 4a to 4e show representations for the production of a modifiedfilm bag 1. Upper film 2 is turned over along its longitudinal edge andwelded along the edge of the turned over part with a longitudinal seam21, thereby forming channel 10. Longitudinal seam 21 is interrupted atintervals so that openings 4 to chambers 7 are later located there, asshown in FIG. 4c, coming to lie between the chamber corners. Accordingto FIG. 4a, a flap 22 of the turned over part of upper film 2 stillremains beside weld seam 21. Upper film 2 is then placed on lower film 3as in FIG. 4b and welded to lower film 3 with longitudinal seams 5 andtransverse seams 6. Left longitudinal weld seam 5 thereby interconnectslower film 3, the turned over part of upper film 2 and the latteritself. When welding transverse seams 6 one must again make sure channel10 remains permeable at the points of passage.

This results in a film bag whose channel 10 is located on the left edge.When air is pressed into channel 10 it passes via openings 4 intochambers 7 of the bag; cf. FIG. 4d. After the end of the inflationprocess, channel 10 is automatically closed in accordance with FIG. 4e.The arrangement of channel 10 in the edge area of the film bag again hasthe advantage that the curves are greatest there when the chambers areinflated so that a sealing effect arises.

In this embodiment example it is also possible to employ only one filminstead of an upper and lower film 2, 3. This single film is then turnedover, as indicated by broken lines in FIG. 4a, and welded with its outeredge in the area of channel 10 to the films thereof. Longitudinal seam 5shown on the right in FIGS. 4b to 4e is then omitted.

FIGS. 5a and 5b show a modified film bag 1b with three chambers 7. Toinflate the chambers a main channel 10 running through all chambers 7 isprovided from which a parallel side channel 14 separated by a weld seam50 branches off in each chamber. The channel arrangement is locatedalong the edge of the film bag. Main channel 10, which is closed on oneside by a continuous longitudinal weld seam 55, remains permeable at thepoints of passage through transverse seams 6 between the individualchambers, while side channels 14 are closed there. Main channel 10 isbroadened at its points of passage at transverse seams 6 by a kind ofsluice 51 in each case, which leads into the side channel and is formedby slanting weld seam 50. When air is introduced into main channel 10 asindicated by the arrow, it passes into the side channel and finallyarrives at opening 4 in the corner of the film bag directly beside theblowing-in point. Shortly before opening 4 a constriction 52 can also beprovided in the side channel, which is produced e.g. by an oblique weldseam 53. This increases the sealing effect since the greatest foldcaused by the closing of the channel arises near to or in the corner.The bag is produced with an upper film 2, a lower film 3 and a filmstrip 8 within the area of which the channels are provided. All threefilms are interconnected on the outside at the edge by the weld seam,film strip 8 is connected by weld seams 50 and 55 with one of thechamber films, in this case upper film 2. It is also possible toprefabricate the channel arrangement by accordingly welding two filmstrips and then welding upper and lower films 2, 3 to a longitudinaledge of the prefabricated channel arrangement in each case.

FIGS. 6a and 6b show a further film bag 1c with a plurality of chambers7. One sees longitudinal weld seams 5 limiting chambers 7 and transverseweld seams 6. Beyond longitudinal weld seam 5 on the left in this case,a main channel extends which is limited at the edge by a longitudinalweld seam 71. Main channel 10 is again divided by an interruptedlongitudinal weld seam 72, forming an intermediate channel 73 betweenmain channel 10 and longitudinal weld seam 5. Longitudinal weld seam 5has an opening 74 so that air from the intermediate channel can flowthere into a side channel 14 located in the film bag. Side channel 14 islimited by a longitudinal weld seam 75 which approaches the chambercorners so that small connecting openings 4 arise here between sidechannel 14 and chamber 7.

FIG. 6b indicates that the film bag is formed in the channel area ofupper film 2, lower film 3 and a film strip 8, the film strip beingplaced between the two films and welded thereto as described above.

FIGS. 7a and 7b show a double bag 1d consisting of two film bagsinterconnected by the channel arrangement. The channel arrangementconsists of a central main channel 10 connected on each side withintermediate channels 85, 86 and 87, 88 separated from each other byinterrupted longitudinal weld seams 81, 82, 83 and 84. In the area oftransverse weld seams 6, longitudinal weld seams 5 of the film bag areinterrupted, giving rise to a connection 89 to a side channel 14. Sidechannel 14 comprises two channels 14a and 14b separated from each otherby a weld seam 90 and interconnected by a constriction 52 in one cornerof chamber 7. At the end of channel 14b the opening into the chambers isagain provided in the channel corner, so that this opening 4 isapproximately opposite entrance port 89. The air which is blown intomain channel 10 and evenly distributed thereby over intermediatechannels 85 to 88 is guided into the chamber in channels 14a and 14b ina loop which in this case leads over the total chamber length.

FIG. 8 shows the top view of part of a film bag 1e. Here, too, mainchannel 10 is located outside the chambers parallel to theirlongitudinal weld seam 5. The main channel is divided by interruptedweld seams 91 and 92 as in the above embodiment example, resulting inintermediate channels 93 and 94 extending toward the edge of thechambers. Longitudinal weld seam 5 is again interrupted, forming anadmission port 95 from intermediate channel 94 into chamber 7. From thisadmission port 95, a short side channel 14 is directed toward thechannel corner, this side channel 14 being constricted at its end in thearea of the channel corner by an oblique weld seam 96, forming a narrowopening 4 into chamber 7 there. When the film bag is inflated one ormore folds form there which reliably seal side channel 14 from theoutside.

FIG. 9 shows a film bag 1f whose main channel is constructed as in theembodiment example of FIG. 8 and accordingly has two intermediatechannels 93 and 94. The longitudinal seam limiting chambers 7 isinterrupted in the area of one corner, giving rise to an admission port95. From this admission port 95 a side channel 14 extends in a meandershape, being formed by meshing weld seams 97. At the beginning ofchannel 14 there is a constriction 98, and opening 4 into the interiorof the chamber is provided at the end of this channel in the vicinity ofthe corner. In this embodiment example one clearly sees that when thefilm bag is inflated the cushion-like deformation of the chambers in thearea of side channel 14 deforms, bends and folds the bag to such anextent as to ensure reliable closure of side channel 14.

FIG. 10 shows part of a film bag 1g which has a main channel 10 situatedoutside the chamber parallel to longitudinal seam 5. As in theembodiment example of FIG. 8, a side channel 14 limited by alongitudinal seam 111 is located in the area of the chambers on theother side of longitudinal seam 5. Longitudinal seam 5 of the film bagis interrupted at several places in the area of side channel 14 so thatentrance points 112 into side channel 14 exist here. Side channel 14 isagain directed into a corner of the chamber and has a constrictionformed by an oblique seam 113 there. Opening 4 of side channel 14 intochamber 7 is also located there. This embodiment requires low weldingenergy since only it is limited to the most necessary weld seams.

FIGS. 11a and 11b show the front end of a metal inflating rod 101.Shortly before the end of the inflating rod there is a rubber casing 102in area a which is firmly connected with the rod on either side. In themiddle of area a the rod is made impermeable to air e.g. by a partition103. In front of and behind this partition 103 openings 104 and 105 arebored into the rod, whereby opening 105 is larger than opening 104. Exitpoint 106 at the tip of the rod is continuously adjustable.

When the air flows through rod 101 it exits through opening 104,inflates rubber casing 102 and passes through opening 105 into the rodagain to escape through outlet opening 106. Depending on the adjustmentof outlet opening 106, the inflated area, i.e. the volume of rubbercasing 102, is large or small. Inflating rod 101 is inserted with itsconical front end into main channel 10 of a film bag.

We claim:
 1. An inflatable film bag for packaging purposescomprising:first and second elongate film portions, one overlying theother, defining a longitudinal direction and a transverse direction, atleast one longitudinal edge of said first and second film portions beinginterconnected with one another by a first longitudinal seam, said firstand second elongate film portions having a plurality of transverse seamswhich, with said first longitudinal seam, define a plurality ofsubstantially rectangular inflatable chambers formed between said firstand second film portions and sequentially arranged along said inflatablefilm bag in the longitudinal direction, a fluid supply channel extendingin the longitudinal direction, along the entire length of saidinflatable film bag and located adjacent said first longitudinal seam,for inflating said plurality of chambers of said film bag with a medium,each of said plurality of chambers having at least one fill openingcommunicating with said supply channel to allow the medium to enter intoeach of said plurality of chambers, and each said filling openingautomatically closing, after completion of the inflating process, due toan internal pressure within each respective chamber, wherein each ofsaid plurality of chambers has a said filling opening interconnectedwith said supply channel via at least one channel branch, and each saidat least one channel branch is located adjacent said first longitudinalseam and is configured so that each said at least one channel branchwill sufficiently bend and crease, as said film bag is deformed duringinflation, thereby creating a high flow resistance from the interior ofeach said chamber to the exterior environment.
 2. An inflatable film bagaccording to claim 1, wherein each inflatable chamber further comprisesa film strip connected to at least one of said first and second filmportions by a further longitudinal seam to define, at least partially,each of said at least one channel branch between said film strip and oneof said first and second film portions, and each said at least onechannel branch communicates with said supply channel, via a feedopening, to facilitate flow of the medium from said supply channel,through said feed opening, into said at least one channel branch andthrough said filling opening into said chamber.
 3. An inflatable bagaccording to claim 2, wherein each said at least one channel branchextends substantially in the longitudinal direction, for substantiallythe entire length of said chamber.
 4. An inflatable film bag accordingto claim 1, wherein each of said plurality of chambers has a feedopening located substantially midway between the two opposed transverseseams partially defining each of said chamber, and two opposed fillingopenings communicating with said at least one channel branch areprovided, and a said filling opening is located in each corner adjacentsaid first longitudinal seam and one of said two opposed transverse seamof each said chamber such that the filling medium flows from said supplychannel, through said feed opening, into said at least one channelbranch and then branches into two opposed longitudinal directions andflows through a said fill opening and into said chamber.
 5. Aninflatable bag according to claim 1, wherein each of said chambers has afeed opening located adjacent said first longitudinal seam andsubstantially in a first corner of each said chamber, and a fillingopening in a second opposed corner of each said chamber adjacent saidfirst longitudinal seam so that said filling medium flows substantiallyalong the longitudinal direction in said channel branch from said feedopening to said fill opening.
 6. An inflatable bag according to claim 1,wherein each of said chambers has two parallel longitudinally extendingchannel branches with each channel branch substantially extending theentire length of said chamber, said two channel branches areinterconnected at one end by a U-shaped member adjacent said firstlongitudinal seam to form a U-shaped channel branch, a feed openinginterconnects one end of one of said channel branches with said supplychannel and said filling opening interconnects one end of the other ofsaid channel branches with said chamber so that the medium flows along aU-shaped path from said feed opening to said fill opening.
 7. Aninflatable bag according to claim 1, wherein said at least one channelbranch extends parallel to the longitudinal direction for substantiallyless than one half of the entire length of each said chamber so thatsaid at least one channel branch is substantially located in a cornerportion, of each of said chambers, where said feed opening is alsolocated.
 8. An inflatable bag according to claim 1, wherein each of saidchambers has a plurality of parallel extending channel branches locatedsubstantially in a corner portion of each of said chambers where saidfeed opening is also located and said plurality of channel branches areinterconnected end to end with one another to forming a serpentine pathwith said feed opening located at one end of the serpentine path and thefilling opening located at the opposite end of the serpentine path. 9.An inflatable bag according to claim 1, wherein a plurality of feedopenings are provided between said supply channel and said at least onechannel branch of each of said chambers.
 10. An inflatable bag accordingto claim 1, wherein said first longitudinal seam separates said supplychannel from said plurality of the chambers so that said supply channelis located outside of said plurality of the chambers and said fillingopenings are formed at seam interruptions along said first longitudinalseam.
 11. An inflatable bag according to claim 1, wherein at least oneinterrupted longitudinal seam is provided between said supply channeland said at least one channel branch.
 12. An inflatable bag according toclaim 1, wherein said at least one channel branch is located adjacentsaid first longitudinal seam, on the same side as said plurality ofchambers, and said supply channel is located adjacent said channelbranches on an opposite side of the first longitudinal seam.
 13. Aninflatable bag according to claim 1, wherein constrictions are providedin said at least one channel branch adjacent said filling opening. 14.An inflatable film bag according to claim 1, wherein said elongate firstand second film portions are two separate films welded together by asecond longitudinal seam.
 15. An inflatable film bag according to claim1, wherein said elongate first and second film portions are part of asingle film which is folded over and the fold forms one of thelongitudinal edges of said inflatable film bag.
 16. An inflatable filmbag according to claim 1, wherein said at least one channel branch is atleast partially defined by at least one of said first and second filmportions.
 17. An inflatable film bag according to claim 1, wherein saidsupply channel is formed by the first longitudinal seam and a secondadjacent longitudinal seam and at least one intermittent seam isprovided therebetween.
 18. An inflatable bag according to claim 1,wherein each of said chambers has two parallel longitudinally extendingchannel branches, said two channel branches are interconnected at oneend by a U-shaped member adjacent said first longitudinal seam to form aU-shaped channel branch, a feed opening interconnects one of saidchannel branches with said supply channel and said filling openinginterconnects the other of said channel branches with said chamber sothat the medium flows along a U-shaped path from said feed opening tosaid fill opening.
 19. An inflatable bag according to claim 1, whereintwo parallel transverse seams separate each of said plurality ofchambers from one another and said two parallel transverse seamsfacilitate bending of said inflatable bag without obstruction.